In order to obtain a hot-rolled steel plate having a desired size, i.e., desired thickness, width and length through hot rolling, it is necessary to provide a material for hot rolling having prescribed thickness, width and length. For the purpose of obtaining a material for hot rolling having prescribed width and length, the following methods are known:
(1) A method for cutting off a continuously cast strand, disclosed in Japanese Patent Publication No. 42,732/78 dated Nov. 14, 1978, which comprises:
(i) reducing a cast strand in cross-section from above and below by a pair of rolls having at the middle a V-shaped cross-section annular projection during continuous casting immediately after passing through the withdrawal rolls or the straightening rolls in a continuous casting installation, to form a V-shaped cross-section groove on each of the top and bottom surfaces of the cast strand along the longitudinal direction of the cast strand; PA1 (ii) gas-cutting the V-shaped groove portion of the cast strand in the longitudinal direction thereof by a "stationary" gas cutting means; and, PA1 (iii) gas-cutting each of the two resultant cut pieces into prescribed lengths;
(hereinafter referred to as the "prior art (1)").
In the prior art (1), it is certainly possible to cut a cast strand in the longitudinal and width directions thereof. In the prior art (1), however, since the cast strand should be gas-cut, the yield becomes lower and it is necessary to remove dross depositing onto the cut surface. Also in the prior art (1), the use of a pair of rolls for forming a V-shaped groove on a cast strand limits the cut width of the cast strand.